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Objective To investigate the effect of couch rotation angle on non-coplanar static intensity-modulated radiotherapy (IMRT) plan for gastric cancer and to provide a reference for clinical planning. Methods A retrospective analysis was conducted on patients who recently underwent postoperative IMRT for gastric cancer. Twenty patients who received radiotherapy in the centre of Radiation Oncology of Huanggang Central Hospital from August 2022 to January 2023 were selected. That were selected to receive a seven-field coplanar static IMRT plan based on a couch rotation angle of 0° as the control group. Then, based on the coplanar IMRT plan, only the couch rotation angle of gantry angles 30° and 330° was changed to 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, and 90°, respectively, and nine different non-coplanar plans were established. The homogeneity index (HI), conformity index (CI) of the target volume, and monitor unit (MU), as well as Dmean, V20, and V30 of the left and right kidneys, Dmax, Dmean, V10, V20, and V30 of the spinal cord, and Dmax, Dmean, V10, V20, V30, and V40 of the small intestine and liver were compared among the 10 plans. The MU and the dosimetric parameters of the target volumes and When the couch rotation angle was 60°, the minimum HI and maximum CI of the target volume were 0.0714±0.0089 and 0.9271±0.0108, respectively, and the minimum MU was 438±26, with the best homogeneity and conformity in the target volume and the shortest machine treatment time (P＜0.05). When the couch rotation angle was 10°, the Dmax of the small intestine was lowest, being (4620.73±99.27) cGy. When the couch rotation angle was 60°, the Dmean of the left and right kidneys was lowest, being (1246.30±130.35) cGy and (1001.52±103.33) cGy, respectively; the V20 of the left and right kidneys was lowest, being 22.87±6.29 and 19.69±1.84, respectively; the V10 and V30 of the spinal cord were lowest, being 40.08±4.92 and 1.68±0.34, respectively (P＜0.05). Conclusion The couch rotation angle has some influence on the postoperative treatment planning for patients with gastric cancer. In the design of non-coplanar plan for gastric cancer, the couch rotation angle of 60° contributes to establishing a better radiotherapy plan.
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Objective:To evaluate the application value of deep deconvolutional neural network (DDNN) model for automatic segmentation of target volume and organs at risk (OARs) in patients with nasopharngeal carcinoma (NPC).Methods:Based on the CT images of 800 NPC patients, an end-to-end automatic segmentation model was established based on DDNN algorithm. Ten newly diagnosed with NPC were allocated into the test set. Using this DDNN model, 10 junior physicians contoured the region of interest (ROI) on 10 patients by using both manual contour (MC) and DDNN deep learning-assisted contour (DLAC) methods independently. The accuracy of ROI contouring was evaluated by using the DICE coefficient and mean distance to agreement (MDTA). The coefficient of variation (CV) and standard distance deviation (SDD) were rendered to measure the inter-observer variability or consistency. The time consumed for each of the two contouring methods was also compared.Results:DICE values of gross target volume (GTV) and clinical target volume (CTV), MDTA of GTV and CTV by using DLAC were 0.67±0.15 and 0.841±0.032, (0.315±0.23) mm and (0.032±0.098) mm, respectively, which were significantly better than those in the MC group (all P<0.001). Except for the spinal cord, lens and mandible, DLAC improved the DICE values of the other OARs, in which mandible had the highest DICE value and optic chiasm had the lowest DICE value. Compared with the MC group, GTV, CTV, CV and SDD of OAR were significantly reduced (all P<0.001), and the total contouring time was significantly shortened by 63.7% in the DLAC group ( P<0.001). Conclusion:Compared with MC, DLAC is a promising method to obtain superior accuracy, consistency, and efficiency for the GTV, CTV and OAR in NPC patients.
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Objective To compare the dosimetric characteristics of non-coplanar and coplanar field technology in static intensity-modulated radiotherapy of gastric cancer patients, so as to provide a reference for clinical radiotherapy plan selection. Methods Thirty-six patients with gastric cancer were selected to receive intensity-modulated radiotherapy in Huanggang Central Hospital, which was designed plan A and B. Group A used 7-field coplanar technology, while Group B used 7-field non-coplanar technology. We compared the differences of the optimized monitor unit, the dosimetry of organs at risk and target areas between group A and group B. Results Both group A and B could meet the requirements of doctors. The homogeneity index (0.14 ± 0.02), the conformity index (0.98 ± 0.01), Dmin (4315.21 ± 16.74) cGy、Dmean (4679.28 ± 28.39) cGy and Dmax(4952.30 ± 33.26) cGy of target areas in group B were better than those of group A. Moreover, the monitor unit of group B was much lower than that of group A, and the difference was statistically significant (P < 0.05). The Dmax, Dmean, V15, V20 and V30 of the left and right kidneys in group B were lower than those of group A. The Dmax (3408.57 ± 46.03) cGy, Dmean (1250.32 ± 14.27) cGy and V20 (44.91% ± 6.67%) of spinal cord and the Dmax (3408.57 ± 46.03) cGy, Dmean (1720.55 ± 17.42) cGy, V20 (25.31% ± 7.78%) and V30 (18.52% ± 1.56%) of small intestine were also lower than those of group A. The differences were statistically significant (P < 0.05). Conclusion The non-coplanar field radiation plan has more advantages in terms of target dose distribution and protection of organs so that it can be more considerably used in the process of planning and design.
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Objective: To study the value of CT-MRI image fusion technique using MIM software in accurate radiotherapy of glioma. Methods: Thirty patients with glioma admitted to the Department of Radiotherapy, The First Affiliated Hospital of Xi'an Jiaotong University, from October 2016 to December 2018 were selected for image fusion of CT and MRI using MIM software system image fusion function. After the fusion was completed, the same radiotherapy doctor performed the target area delineation of CT images and CT-MRI fusion images of each patient, used the same treatment planning system to make two different treatment plans for each patient, and compared the difference in target volume, the dosimetric difference in the target area and the dose difference in the organs at risk between the two groups of delineations. Results: The volumes of GTVCT, CTVCT and PTVCT delineated under CT images were significantly larger than those of GTVCT+MRI, CTVCT+MRI and PTVCT-MRI under CT-MRI fusion images (P<0.05). The maximum dose and mean dose of PTV in CT image group plan were higher than those in CT-MRI fusion image group plan (P<0.05). Except the right lens, right optic nerve, and right eyeball, the maximum dose and mean dose of OARs (brain stem, optic chiasm, pituitary, left optic nerve, left lens, and left eyeball) of CT image group plan were significantly greater than those of the CT-MRI fusion image group plan(P<0.05). Results: In the IMRT radiotherapy of glioma, the application of MIM software CT-MRI image fusion technology can improve the rationality and accuracy of target delineation and plan making, and can effectively reduce the radiation dose of normal tissues and improve the protection of normal tissues.
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When applying deep learning to the automatic segmentation of organs at risk in medical images, we combine two network models of Dense Net and V-Net to develop a Dense V-network for automatic segmentation of three-dimensional computed tomography (CT) images, in order to solve the problems of degradation and gradient disappearance of three-dimensional convolutional neural networks optimization as training samples are insufficient. This algorithm is applied to the delineation of pelvic endangered organs and we take three representative evaluation parameters to quantitatively evaluate the segmentation effect. The clinical result showed that the Dice similarity coefficient values of the bladder, small intestine, rectum, femoral head and spinal cord were all above 0.87 (average was 0.9); Jaccard distance of these were within 2.3 (average was 0.18). Except for the small intestine, the Hausdorff distance of other organs were less than 0.9 cm (average was 0.62 cm). The Dense V-Network has been proven to achieve the accurate segmentation of pelvic endangered organs.
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Humans , Algorithms , Image Processing, Computer-Assisted , Imaging, Three-Dimensional , Neural Networks, Computer , Organs at Risk , Pelvis , Tomography, X-Ray ComputedABSTRACT
Objective To study a method for verifying the doses to PTV and OAR as well as the 2D dose distribution arising from IMRT through using radiochromic films and TLDs.Methods Totally 7 medical electronic linear accelerators from Varian,Siemens and Elekta were selected.The polystyrene phantom provided by IAEA was conducted with CT scan.After irradiation with 6 MV X-rays,the TLDs and films were returned to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.Results According to the IAEA requirements,the relative deviations between TLD-measured and TPS-planned values for PTV and OAR doses were both within ±7.0％.For PTV,the measured relative deviations for 5 accelerators were in the range of-4.0％ to 3.4％,consistent with the IAEA requirements,whereas the values for the other 2 accelerators were in the range of-7.0％ to 10.6％,not consistent with the requirements.For OAR,the values for 4 accelerators were in the range of-5.6％ to 3.3％,consistent with the IAEA requirements,whereas the values for the other 3 accelerators were in the range of-20.8％ to 11.5％,not meeting the requirements.As required by the IAEA,the 2D dose distribution 3 mm/3％ pass rate should be higher than 90％.The measured values for 5 accelerators were in the range of 91.8％ to 98.5％,consistent with the requirements,whereas the values measured for the other 2 were 45.0％ and 77.0％ respectively,not meeting the requirements.Conclusions It is feasible for using TLDs and radiochromic films to verify the doses to PTV and OAR and the 2D dose distribution in IMRT.This method should be applied to not only quality verification but also hospital internal audit to the extent possible.
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Objective To use TLDs and radiochromic films to verify the prescribed doses to both planned target volume (PTV) and organ at risk (OAR) and the 2D dose distribution in IMRT.Methods Eight accelerators of different models were selected in Henan province.The polystyrene phantom provided by IAEA was scanned using CT scanners and then the scanned images were transmitted to treatment planning system (TPS) for prescribing respectively the doses to PTV and OAR.IMRT was performed with phantom exposed to a 6 MV X-rays.The irradiated TLDs and films were delivered for measurement and estimation at Secondary Standard Dosimetry Laboratory at National Institute for Radiological Protection,Chinese Center for Disease Control and Prevention.Results According to IAEA requirements,the relative deviations of the TLD-measured and TPS-planned values were within ±7.0％ for the prescribed doses to PTV and OAR.The measured results for PTV have shown that the relative deviation of TLD-measured and TPS-planned values were within-0.3％ to 6.9％ for 8 accelerators,all consistent with the IAEA requirements.For OAR,the relative deviations of TLD-measured and TPS-planned were within-7.0％ to 0.3％ for 6 accelerators,consistent with the requirements,whereas those for other 2 accelerators were within-10.8％ to-8.4％,not up to the requirements.IAEA required that,for 2D dose distribution,the pass rate of 3 mm/3％ be ≥ 90％.The measured values for 7 accelerators were from 90.2％ to 99.9％,consistent with the requirements,whereas that for another one was 70.0％,not meeting the requirement.Conclusions The method to verify,using radiochromic film and TLD,the prescribed doses to PTV and OAR and the pass rate of 2D dose distribution is simple and reliable.It is an important step to implement quality control for IMRT and can provide effective support for medical or third-party service institution to verify clinically prescribed dose.
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Objective To study a method to measure the doses to planned target volume (PTV) and organ at risk (OAR) and 2D dose distribution in IMRT by using TLD and radiochromic film for a verification purpose.Methods Totally 7 different types of medical linear accelerators were selected from seven hospitals in Hubei province.A polystyrene phantom provided by IAEA was CT scanned and then the scanned images were returned to the Treatment Planning System (TPS) for determining the prescribed doses to PTS and OAR and the corresponding MU.After the phantom was irradiated with 6 MV X-ray,the TLDs and films were transmitted to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.Results The IAEA required the relative deviations between TLD-measured and TPS-planned doses to OAR and PTV be within ±7.0％.For PTV,the measured-to-planned deviation values for 7 accelerator were within-5.4％ to 6.5％,all consistent with the IAEA requirements.For OAR,the values for 5 accelerators were within-2.2％ to 6.7％,not consistent the requirements,whereas the values for the other 2 were-8.6％ and 8.2％ respectively,beyond the required values.The IAEA required that the 2D dose distribution 3 mm/3％ pass rate be higher than 90％.The measured values for 7 accelerators were in the range of 90.3％-98.9％,all consistent with the requirements.Conclusions It is feasible scientifically and easy to operate in practice for using TLD and film to carry out dose verification in IMRT.It would be advisable to apply this method to quality verification in IMRT in medical institutions to the extent possible.
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Objective To validate the method for measuring the TPV and OAR doses and 2D dose distribution in IMRT through using TLD and radiochromic film.Methods Eight medical linear accelerators (Valian,Elekta,Siemens) were selected.The polystyrene phantom provided by IAEA was CT scanned and the image obtained was transferred to TPS for formulation of treatment plan,prescription of PTV and OAR doses and calculation of corresponding monitoring unit (MU),IMRT was performed on the phantom using 6 MV X-ray.Irradiated TLDs and films were measured and evaluated at the Secondary Standard Dosimetry Laboratory at the Radiation Safety Institute of Chinese Center for Disease Control and Prevention.Results According to IAEA requirement,the relative deviations between TLD-measured and TPS-planned doses were within ±7.0％ for the prescribed PTV and OAR doses.As measured result,the PTV values for 8 accelerators were in the range of 0.6％ to 5.9％,consistent with the IAEA requirements,whereas the OAT values for 8 accelerators were within-0.6％ to 7.0％,consistent the requirements.As IAEA required,the 2D dose distribution passing rate of 3 mm/3％ should be higher than 90％.The filmmeasured and TPS-planned values for 8 accelerators were within 90.2％ to 100.0％,consistent with the requirements.Conclusions TLD and radiochromic film are feasible in validating the PTV and OAR doses and the 2D dose distribution pass rate in IMRT.This method can be widely used in quality audit and internal verification in IMRT in medical institutiions on a large scale.
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Objective To develop the methodology for using TLD and radiochromic film to measure the planned target volume (PTV) and organ at risk (OAR) doses and 2D dose distribution in IMRT,in order to provide technical guidance on the dose quality audit in IMRT at home.Methods China has participated in the research project launched by the international multi-radiotherapy centre (IMRC).IMRT polystyrene phantom provided by IAEA was scanned by CT scanner and then the scanned images were transmitted to TPS to outline prescribed dose to PTV and to OAR.The former was limited to 400 cGy while the latter limited to 200 cGy.IMRT was implemented with the phantom irradiated using 6 MV X-ray.The irradiated TLDs and films were sent to IAEA dosimerty laboratory for measurement and calculation.Jiangsu,Sichuan,Hubei and Henan provinces were selected to engage with this study for their variety of accelerators and highly skilled physicists.The procedures used were the same as in the IMRC and the irradiated TLDs and films were required to send to external audit group for measurement and calculation.Results According to IAEA requirement,the relative deviations of the TLD-measured and TPS planned doses are within ±7.0％ for PTV and OAR.The China's research results at the IMRC have shown that the relative deviation of TLD-measured and TPS-planned values for the upper and lower PTV were-0.2％ and 0.8％,respectively,consistent with the IAEA requirement,and the values for upper and lower OAR were -0.6％ and-1.0％,respectively,consistent with the requirement.As the results have shown in four provinces,the relative deviations of the TLD-measured and TPS-planned were within 0 to 10.6％ for upper and lower PTV and-0.6％ to 20.9％ for upper and lower OAR.According to IAEA requirement,the passing rate should be greater than 90％ for 3 mm /3％ for 2D dose distribution.China's result at the IMRC is 100％,being excellent.The four provinces' results have shown that 2D dose distribution pass rate of 3 mm/3％ was in the range of 45.0％-100.0％.Conclusions The uses of TLD in quality audit for PTV and OAR doses and the radiochromic film in 2D dose distribution pass rate in IMRT are characterized by scientific feasibility,strong operability,easy-to-mail and data realibility.They are can be applied to quality assurance and audit in medical institutions in the country to on a large scale.
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Objective@#To study a method for verifying the doses to PTV and OAR as well as the 2D dose distribution arising from IMRT through using radiochromic films and TLDs.@*Methods@#Totally 7 medical electronic linear accelerators from Varian, Siemens and Elekta were selected. The polystyrene phantom provided by IAEA was conducted with CT scan. After irradiation with 6 MV X-rays, the TLDs and films were returned to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.@*Results@#According to the IAEA requirements, the relative deviations between TLD-measured and TPS-planned values for PTV and OAR doses were both within ±7.0%. For PTV, the measured relative deviations for 5 accelerators were in the range of -4.0% to 3.4%, consistent with the IAEA requirements, whereas the values for the other 2 accelerators were in the range of -7.0% to 10.6%, not consistent with the requirements. For OAR, the values for 4 accelerators were in the range of -5.6% to 3.3%, consistent with the IAEA requirements, whereas the values for the other 3 accelerators were in the range of -20.8% to 11.5%, not meeting the requirements. As required by the IAEA, the 2D dose distribution 3 mm/3% pass rate should be higher than 90%. The measured values for 5 accelerators were in the range of 91.8% to 98.5%, consistent with the requirements, whereas the values measured for the other 2 were 45.0% and 77.0% respectively, not meeting the requirements.@*Conclusions@#It is feasible for using TLDs and radiochromic films to verify the doses to PTV and OAR and the 2D dose distribution in IMRT. This method should be applied to not only quality verification but also hospital internal audit to the extent possible.
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Objective@#To use TLDs and radiochromic films to verify the prescribed doses to both planned target volume (PTV) and organ at risk (OAR) and the 2D dose distribution in IMRT.@*Methods@#Eight accelerators of different models were selected in Henan province. The polystyrene phantom provided by IAEA was scanned using CT scanners and then the scanned images were transmitted to treatment planning system (TPS) for prescribing respectively the doses to PTV and OAR. IMRT was performed with phantom exposed to a 6 MV X-rays. The irradiated TLDs and films were delivered for measurement and estimation at Secondary Standard Dosimetry Laboratory at National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention.@*Results@#According to IAEA requirements, the relative deviations of the TLD-measured and TPS-planned values were within ±7.0% for the prescribed doses to PTV and OAR. The measured results for PTV have shown that the relative deviation of TLD-measured and TPS-planned values were within -0.3% to 6.9% for 8 accelerators, all consistent with the IAEA requirements. For OAR, the relative deviations of TLD-measured and TPS-planned were within -7.0% to 0.3% for 6 accelerators, consistent with the requirements, whereas those for other 2 accelerators were within -10.8% to -8.4%, not up to the requirements. IAEA required that, for 2D dose distribution, the pass rate of 3 mm/3% be ≥90%. The measured values for 7 accelerators were from 90.2% to 99.9%, consistent with the requirements, whereas that for another one was 70.0%, not meeting the requirement.@*Conclusions@#The method to verify, using radiochromic film and TLD, the prescribed doses to PTV and OAR and the pass rate of 2D dose distribution is simple and reliable. It is an important step to implement quality control for IMRT and can provide effective support for medical or third-party service institution to verify clinically prescribed dose.
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Objective@#To study a method to measure the doses to planned target volume (PTV) and organ at risk (OAR) and 2D dose distribution in IMRT by using TLD and radiochromic film for a verification purpose.@*Methods@#Totally 7 different types of medical linear accelerators were selected from seven hospitals in Hubei province. A polystyrene phantom provided by IAEA was CT scanned and then the scanned images were returned to the Treatment Planning System (TPS) for determining the prescribed doses to PTS and OAR and the corresponding MU. After the phantom was irradiated with 6 MV X-ray, the TLDs and films were transmitted to the secondary standard dosimetry laboratory of China CDC for measurement and estimation.@*Results@#The IAEA required the relative deviations between TLD-measured and TPS-planned doses to OAR and PTV be within ±7.0%. For PTV, the measured-to-planned deviation values for 7 accelerator were within -5.4% to 6.5%, all consistent with the IAEA requirements. For OAR, the values for 5 accelerators were within -2.2% to 6.7%, not consistent the requirements, whereas the values for the other 2 were -8.6% and 8.2% respectively, beyond the required values. The IAEA required that the 2D dose distribution 3 mm/3% pass rate be higher than 90%. The measured values for 7 accelerators were in the range of 90.3%-98.9%, all consistent with the requirements.@*Conclusions@#It is feasible scientifically and easy to operate in practice for using TLD and film to carry out dose verification in IMRT. It would be advisable to apply this method to quality verification in IMRT in medical institutions to the extent possible.
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Objective@#To validate the method for measuring the TPV and OAR doses and 2D dose distribution in IMRT through using TLD and radiochromic film.@*Methods@#Eight medical linear accelerators (Valian, Elekta, Siemens) were selected. The polystyrene phantom provided by IAEA was CT scanned and the image obtained was transferred to TPS for formulation of treatment plan, prescription of PTV and OAR doses and calculation of corresponding monitoring unit (MU), IMRT was performed on the phantom using 6 MV X-ray. Irradiated TLDs and films were measured and evaluated at the Secondary Standard Dosimetry Laboratory at the Radiation Safety Institute of Chinese Center for Disease Control and Prevention.@*Results@#According to IAEA requirement, the relative deviations between TLD-measured and TPS-planned doses were within ±7.0% for the prescribed PTV and OAR doses. As measured result, the PTV values for 8 accelerators were in the range of 0.6% to 5.9%, consistent with the IAEA requirements, whereas the OAT values for 8 accelerators were within -0.6% to 7.0%, consistent the requirements. As IAEA required, the 2D dose distribution passing rate of 3 mm/3% should be higher than 90%. The film-measured and TPS-planned values for 8 accelerators were within 90.2% to 100.0%, consistent with the requirements.@*Conclusions@#TLD and radiochromic film are feasible in validating the PTV and OAR doses and the 2D dose distribution pass rate in IMRT. This method can be widely used in quality audit and internal verification in IMRT in medical institutiions on a large scale.
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Objective@#To develop the methodology for using TLD and radiochromic film to measure the planned target volume (PTV) and organ at risk (OAR) doses and 2D dose distribution in IMRT, in order to provide technical guidance on the dose quality audit in IMRT at home.@*Methods@#China has participated in the research project launched by the international multi-radiotherapy centre (IMRC). IMRT polystyrene phantom provided by IAEA was scanned by CT scanner and then the scanned images were transmitted to TPS to outline prescribed dose to PTV and to OAR. The former was limited to 400 cGy while the latter limited to 200 cGy. IMRT was implemented with the phantom irradiated using 6 MV X-ray. The irradiated TLDs and films were sent to IAEA dosimerty laboratory for measurement and calculation. Jiangsu, Sichuan, Hubei and Henan provinces were selected to engage with this study for their variety of accelerators and highly skilled physicists. The procedures used were the same as in the IMRC and the irradiated TLDs and films were required to send to external audit group for measurement and calculation.@*Results@#According to IAEA requirement, the relative deviations of the TLD-measured and TPS planned doses are within ±7.0% for PTV and OAR. The China′s research results at the IMRC have shown that the relative deviation of TLD-measured and TPS-planned values for the upper and lower PTV were -0.2% and 0.8%, respectively, consistent with the IAEA requirement, and the values for upper and lower OAR were -0.6% and -1.0%, respectively, consistent with the requirement. As the results have shown in four provinces, the relative deviations of the TLD-measured and TPS-planned were within 0 to 10.6% for upper and lower PTV and -0.6% to 20.9% for upper and lower OAR. According to IAEA requirement, the passing rate should be greater than 90% for 3 mm /3% for 2D dose distribution. China′s result at the IMRC is 100%, being excellent. The four provinces′ results have shown that 2D dose distribution pass rate of 3 mm/3% was in the range of 45.0%-100.0%.@*Conclusions@#The uses of TLD in quality audit for PTV and OAR doses and the radiochromic film in 2D dose distribution pass rate in IMRT are characterized by scientific feasibility, strong operability, easy-to-mail and data realibility. They are can be applied to quality assurance and audit in medical institutions in the country to on a large scale.
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Objective@#To assess the interobserver variations in delineating the planning target volume (PTV) and organs at risk (OAR) using different contouring methods during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC), aiming to provide references for the quality control of multi-center clinical trials.@*Methods@#The PTV and OAR of CT image of 1 NPC patient manually delineated by 10 physicians from 8 different radiation centers were defined as the " manual contour group" , and the OAR auto-contoured using the ABAS software and modified by the physicians were defined as the " auto+ manual contour group" . The maximum/minimum ratio (MMR) of the PTV and OAR volumes, and the coefficient of variation (CV) for different delineated contours were comparatively evaluated.@*Results@#Large variation was observed in the PTV and OAR volumes in the manual contour group. The MMR and CV of the PTV were 1.72-3.41 and 0.16-0.39, with the most significant variation in the PTVnd (MMR=3.41 and CV=0.39 for the PTVnd-L). The MMR and CV of the manually contoured OAR were 1.30-7.89 and 0.07-0.67. The MMR of the temporal lobe, spinal cord, temporomandibular joint, optic nerve and pituitary gland exceeded 2.0. Compared with the manual contour group, the average contouring time in the auto+ manual group was shortened by 68% and the interobserver variation of the OAR volume was reduced with an MMR of 1.04-2.44 and CV of 0.01-0.37.@*Conclusions@#Large variation may occur in the PTV and OAR contours during IMRT plans for NPC delineated by different clinicians from multiple medical centers. Auto-contouring+ manually modification can reduce the interobserver variation of OAR delineation, whereas the variation in the delineation of small organs remains above 1.5 times. The consistency of the PTV and OAR delineation and the possible impact upon clinical outcomes should be reviewed and evaluated in multi-center clinical trials.
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Objective To assess the interobserver variations in delineating the planning target volume (PTV) and organs at risk (OAR) using different contouring methods during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC),aiming to provide references for the quality control of multi-center clinical trials.Methods The PTV and OAR of CT image of 1 NPC patient manually delineated by 10 physicians from 8 different radiation centers were defined as the "manual contour group",and the OAR auto-contoured using the ABAS software and modified by the physicians were defined as the "auto+manual contour group".The maximum/minimum ratio (MMR) of the PTV and OAR volumes,and the coefficient of variation (CV) for different delineated contours were comparatively evaluated.Results Large variation was observed in the PTV and OAR volumes in the manual contour group.The MMR and CV of the PTV were 1.72-3.41 and 0.16-0.39,with the most significant variation in the PTVnd (MMR=3.41 and CV =0.39 for the PTVnd-L).The MMR and CV of the manually contoured OAR were 1.30-7.89 and 0.07-0.67.The MMR of the temporal lobe,spinal cord,temporomandibular joint,optic nerve and pituitary gland exceeded 2.0.Compared with the manual contour group,the average contouring time in the auto+ manual group was shortened by 68％ and the interobserver variation of the OAR volume was reduced with an MMR of 1.04-2.44 and CV of 0.01-0.37.Conclusions Large variation may occur in the PTV and OAR contours during IMRT plans for NPC delineated by different clinicians from multiple medical centers.Auto-contouring+ manually modification can reduce the interobserver variation of OAR delineation,whereas the variation in the delineation of small organs remains above 1.5 times.The consistency of the PTV and OAR delineation and the possible impact upon clinical outcomes should be reviewed and evaluated in multi-center clinical trials.
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BACKGROUND: The purpose of this study was to evaluate the efficacy and feasibility of non-coplanar whole brain radiotherapy (NC-WBRT) for parotid sparing.METHODS: Fifteen cases, previously treated with WBRT were selected. NC-WBRT plans were generated. The beam arrangement for the non-coplanar plans consisted of superior anterior, right, and left beams. After generation of the non-coplanar plans a field-in-field technique was applied to the bilateral parallel opposed beams in order to reduce maximum dose and increase dose homogeneity. The NC-WBRT plans were subsequently compared with the previously generated bilateral WBRT (B-WBRT) plans. A field-in-field technique was also used with the B-WBRT plans according to our departmental protocol. As per our institutional practice a total dose of 30 Gy in 10 fractions of WBRT was administered 5 days a week.RESULTS: The mean dose to the parotid gland for the two different plans were 16.2 Gy with B-WBRT and 13.7 Gy with NC-WBRT (p < 0.05). In the NC-WBRT plan, the V5Gy, V10Gy, V15Gy, V20Gy, and V25Gy of the parotid were significantly lower (p < 0.05) than those of the B-WBRT plan. The Dmax of the lens was also lower by 10% with NC-WBRT.CONCLUSION: The use of NC-WBRT plans could be a simple and effective method to reduce irradiated volumes and improve the dose-volume parameters of the parotid gland.
Subject(s)
Brain , Institutional Practice , Methods , Parotid Gland , Radiotherapy , XerostomiaABSTRACT
Object To study the effects of the number of arcs in the treatment of cervical cancer with volumetric modulated arc therapy (VMAT) on the treatment plan, and to provide reference for the selection of the number of arcs in the clinical application.Methods CT images of 10 patients with cervical cancer were selected, it's the radiation therapist that delineated the target area and organs, the prescribed dose was 5040 cGy per 28 times to the target area, and single arc (Arc1), double arc (Arc2) and three (Arc3) plan were designed by RayStation planning system to compare the differences with the dosimetry characteristics of target and organs. The time required for planning optimization was recorded, and the difference between the monitor unit and the delivery time in the three plans was analyzed. A dose validation tool for PTW was used to verify the dose to analyze the influence of the number of arc on the passing rate of gamma verification.Results Single arc plan (Arc1), double arc plan (Arc2) and three arc plan (Arc3) for 10 cases of cervical cancer all proved to meet the clinical requirements. With the increase of arc number, the target area distribution got improved, V40, V45 and Dmean in the organs at risk of rectum, bladder, and femoral head gradually decreased in case of doses of 40 and 45 Gy, and V35, V40 and V45 in the normal tissue were lowered in case of the doses of 35, 40 and 45 Gy. With the increase of the arc number, the optimization time and the delivery time of the plan increased, while the difference between the monitor unit of the three plans was smaller. The passing rate of the three plans was more than 99.5％, and the difference was small.Conclusion Cervical cancer VMAT plan has the target dose distribution and the protection of organs at risk enhanced with the increase of the number of arcs, while the treatment time and cost increased. Therefore, it is necessary to take comprehensive considerations on the number of VMAT plan arcs.
ABSTRACT
Objective To evaluate the geometric and dosimetric accuracy of autosegmentation software for contouring the organ-at-risk ( OAR) of esophageal cancer, and discuss its clinical feasibility. Methods A total of 10 patients were enrolled, and single and multi-template were adopted respectively to auto-delineate corresponding OARs on target CT images based on image registration. The geometric consistency including volume difference (ΔV) , dice similarity ( DSC) and position difference (Δx, Δy,Δz) between the two autosegmentation method and manual were compared using Wilcoxon signed-rank test. And the correlation between DSC and OAR volume was analyzed. In addition, to evaluate the clinical feasibility of autosegmentation, the dose distributions of all OARs were compared using Friedman test. Results The average DSC of all OARs obtained by single and multi-template were 0.82 ± 0.17 and 0.92 ± 0.54, respectively, with statistically significant difference (Z= -2.803- -2.497, P<0.05). A positive correlation between DSC of the autosegmentation and OAR volume was found by spearman analysis, and the single-template was not good enough for the spinal cord with smaller volume. The positional deviations of multi-template group were less than 0.5 cm in three directions, which were better than single-template group. The main dosimetric indexes of single-template and multiple-template were similar to manual coutours. V20 of whole lung were 23.2％, 22.4％ and 22.1％, Dmeanof whole lung were (11.3 ±4.0), (11.1 ±4.5) and (11.0 ±4.3) Gy, Dmaxof spinal cord were (40.3 ±4.8), (38.2 ±6.7) and (39.4 ± 5.3) Gy, respectively, and V30 of heart were 16.0％, 15.8％ and 15.5％, respectively. There was no statistical difference between the three methods (P>0.05), and all of the dosimetric indexes were in line with the requirements of clinical dose limits. Conclusions The autosegmentation software can achieve satisfactory precision for the OARs of the esophageal cancer patients, and the multi-template method is better than the single-template, which is more suitable for clinical application.